Portable communications products, such as radios, are usually powered by rechargeable battery packs. Such battery packs can be charged by a battery charger based on a variety of parameters such as voltage, battery chemistry, rated capacity, and temperature. While positive and negative charging power line contacts (Batt+ and Batt−) are used for charging and measuring the battery pack voltage, many battery packs also include additional contacts for communicating parameters, such as temperature and charging rate, to the battery charger. Furthermore, battery packs usually includes positive and negative battery power line contacts as well as a parameter status output contact to interface the battery pack to the radio.
Manufacturers of battery chargers have realized that the chargers can be made less sophisticated and less expensive if the battery pack provides some indication of how it should be recharged. One way for transferring battery pack information to the charger with fewer contacts is to produce a battery pack with a memory device. The memory device contains charge instructions and other recharge related data, such as rated capacity and chemistry. When the battery pack is coupled to the charger, the charger retrieves the information from the battery pack's memory and charges the battery pack accordingly. However, if the radio is coupled to the battery pack during charging, the limited number of contacts does not readily allow the current charging status of the battery pack to be provided to the radio for processing and displaying on a display of the radio.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.